Just look around your house and see what you've got for electrical heating appliances. Kettles, frying pans, space heaters, irons, etc. These are nothing but big power resistors. Calculate the resistances and see what kind of series/parallel combinations you can come up with. Old and dumb is better than new and smart because there won't be any electronics involved, just bimetallic thermostats.
Some years ago I picked up a few heating elements from an electric stove. 208/240V @ 1000/1325W means it's a 43R resistor. 208/240V @ 1765/2350W is a 25R resistor. So if you've got a 30V power supply, 25R would give you 1.2 amps @ 36W. I think it can handle that power!
Note that I'm not suggesting that you disassemble your stove. Your significant other might not be impressed. They also might not like seeing a bunch of appliances connected together with clip leads, so proceed cautiously!
Ed